I believe the problem is related to GLSL version and latest Intel HD Graphics driver is using higher version of GLSL, but gl_Vertex does not normalize or the value is just over 1 or less then 0 (eg. 1.00001). Then it causes the crash when running the sampling loop. I am not an expert on GLSL, so I would like to confirm the best solution to handle this problem. Thanks.

My program uses RayTracedTechnique for volume rendering, but it hangs with Intel HD graphics 520, 530 and 620. My old laptop works fine which is using Intel HD Graphic 3000. Other machines with Nvidia cards are working fine too. I believe the problem is on shaders in the sampling loop. My program is using osg 3.2.3. I also tried to upgrade to osg 3.4.1, but the same problem occurred with Intel HD Graphic 520, 530 and 620. Do anyone have similar problem and any solution to fix it? Many thanks.

The gl_Vertex isn't a normalized on any system, osgVolume::RayTracedTechnique does use a unit cube for it's geometry though, so the vertex data should all be in the 0.0f to 1.0f range. Perhaps the intel driver/hardware combination is resulting in some numerical precision issue so that the values are going slightly outside the 0 to 1.0f range, but even if it does I wouldn't expect the fragment shaders to suddenly have problems.

Is there are specific line in the shader that you think is cause the crash?

FYI, osgVolume checks for the shader/volume.vert and shader/volume.frag filenames first then fallsback to the built in shaders that are found in the src/osgVolume/Shaders/volume_frag.cpp. The shader/volume.frag can be found in OpenSceneGraph-Data/shader so if you have this available and it's on the OSG_FILE_PATH then you should be able to edit the shader files without recompiling the application.

Robert.

Robert.

On 1 September 2017 at 08:11, < (

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)> wrote:

Quote:

Hi,

Finally I found where causes the problem. For some reasons, gl_Vertex is not normalized. I looked at osg shader source code (srcosgVolumeShaders). For example, in file volume_frag.cpp,

vec4 t0 = vertexPos;
vec4 te = cameraPos;

// by default te did to check the range (0 and 1), but t0 did not.
// If I added some codes to check the range, then the problem is completed gone.

I believe the problem is related to GLSL version and latest Intel HD Graphics driver is using higher version of GLSL, but gl_Vertex does not normalize or the value is just over 1 or less then 0 (eg. 1.00001). Then it causes the crash when running the sampling loop. I am not an expert on GLSL, so I would like to confirm the best solution to handle this problem. Thanks.

Regards,
Clement Chu

________________________________________
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)> on behalf of <>
Sent: Wednesday, 30 August 2017 17:31
To: (

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My program uses RayTracedTechnique for volume rendering, but it hangs with Intel HD graphics 520, 530 and 620. My old laptop works fine which is using Intel HD Graphic 3000. Other machines with Nvidia cards are working fine too. I believe the problem is on shaders in the sampling loop. My program is using osg 3.2.3. I also tried to upgrade to osg 3.4.1, but the same problem occurred with Intel HD Graphic 520, 530 and 620. Do anyone have similar problem and any solution to fix it? Many thanks.

Since I don't know how to debug or print message in shader code, I am not sure what exact value of vertex. I guess the value of vertex is not in the range (0.0 to 1.0), so texture3D method cannot get correct color value by coordinate. In file volume_frag.cpp, variable texcoord is assigned from vertex data. If vertex data is not the 0.0f to 1.0f range, variable color (type vec4) will become strange value. Even I added some codes to make sure values of color.x, color.y, color.z and color.w in the range (0.0 to 1.0), it still cause the crash. Unless vertex is in the range (0.0 to 1.0). So far, this problem occurs in Intel HD Graphics 520 or above. My old laptop is Intel HD Graphics 3000, but it works fine and Nvidia cards work fine too.

The gl_Vertex isn't a normalized on any system, osgVolume::RayTracedTechnique does use a unit cube for it's geometry though, so the vertex data should all be in the 0.0f to 1.0f range. Perhaps the intel driver/hardware combination is resulting in some numerical precision issue so that the values are going slightly outside the 0 to 1.0f range, but even if it does I wouldn't expect the fragment shaders to suddenly have problems.

Is there are specific line in the shader that you think is cause the crash?

FYI, osgVolume checks for the shader/volume.vert and shader/volume.frag filenames first then fallsback to the built in shaders that are found in the src/osgVolume/Shaders/volume_frag.cpp. The shader/volume.frag can be found in OpenSceneGraph-Data/shader so if you have this available and it's on the OSG_FILE_PATH then you should be able to edit the shader files without recompiling the application.

Robert.

Robert.

On 1 September 2017 at 08:11, < (

Only registered users can see emails on this board!Get registred or enter the forums!

)> wrote:

Quote:

Hi,

Finally I found where causes the problem. For some reasons, gl_Vertex is not normalized. I looked at osg shader source code (srcosgVolumeShaders). For example, in file volume_frag.cpp,

vec4 t0 = vertexPos;
vec4 te = cameraPos;

// by default te did to check the range (0 and 1), but t0 did not.
// If I added some codes to check the range, then the problem is completed gone.

I believe the problem is related to GLSL version and latest Intel HD Graphics driver is using higher version of GLSL, but gl_Vertex does not normalize or the value is just over 1 or less then 0 (eg. 1.00001). Then it causes the crash when running the sampling loop. I am not an expert on GLSL, so I would like to confirm the best solution to handle this problem. Thanks.

Regards,
Clement Chu

________________________________________
From: osg-users < (

Only registered users can see emails on this board!Get registred or enter the forums!

)> on behalf of <>
Sent: Wednesday, 30 August 2017 17:31
To: (

Only registered users can see emails on this board!Get registred or enter the forums!

My program uses RayTracedTechnique for volume rendering, but it hangs with Intel HD graphics 520, 530 and 620. My old laptop works fine which is using Intel HD Graphic 3000. Other machines with Nvidia cards are working fine too. I believe the problem is on shaders in the sampling loop. My program is using osg 3.2.3. I also tried to upgrade to osg 3.4.1, but the same problem occurred with Intel HD Graphic 520, 530 and 620. Do anyone have similar problem and any solution to fix it? Many thanks.

Only registered users can see emails on this board!Get registred or enter the forums!

)> wrote:

Quote:

Since I don't know how to debug or print message in shader code, I am not sure what exact value of vertex. I guess the value of vertex is not in the range (0.0 to 1.0), so texture3D method cannot get correct color value by coordinate. In file volume_frag.cpp, variable texcoord is assigned from vertex data. If vertex data is not the 0.0f to 1.0f range, variable color (type vec4) will become strange value. Even I added some codes to make sure values of color.x, color.y, color.z and color.w in the range (0.0 to 1.0), it still cause the crash. Unless vertex is in the range (0.0 to 1.0). So far, this problem occurs in Intel HD Graphics 520 or above. My old laptop is Intel HD Graphics 3000, but it works fine and Nvidia cards work fine too.

Debugging shaders is *really* hard because you just can't put in break points, print out values, do any of the normal debugging approaches we take for granted on the desktop. So it's a case of think of idea what might be wrong, adapt the shaders to test that, run them app and just and make sense of the results.

The fact that shaders can be loaded and compiled at runtime helps reduce the time takes to see changes so this can help a bit, for yourself I would certainly recommend copying the volume.vert and volume.frag shaders from OpenSceneGraph-Data, put them on your path as use in testing.

Another thing that might help if you are having to put "workaround" code in just for a certain hardware vendor then the vendor string and #pragma(tic) shader composition might be of help. I use this facility to detect and provide a workaround for an NVidia issue - look at how NVIDIA_Corporation is used in the shaders. The osg::State object checks the GL_VENDOR string at runtime and sets a #define with this value that you can then reference using #pragma import_defines(..).

I don't know what the string will be for Intel. Run an OSG application with the OSG_NOTIFY_LEVEL set to INFO and search the console output for a "GL_VENDOR = " entry. You can they use this in the shader mods.

--

On the specific issue of the vertex value clamping, RayTracedTechnique creates a box with dimensons of 0,0,0 to 1,1,1 so there shouldn't be any values outside this being passed to the vertex shader. However, the CPU->driver->GPU might be changing the precision enough that you are getting values outside this range. I find it odd that the shaders would be sensitive to such small precision issues though.

I believe the problem is related to GLSL version and latest Intel HD Graphics driver is using higher version of GLSL, but gl_Vertex does not normalize or the value is just over 1 or less then 0 (eg. 1.00001). Then it causes the crash when running the sampling loop. I am not an expert on GLSL, so I would like to confirm the best solution to handle this problem. Thanks.

My program uses RayTracedTechnique for volume rendering, but it hangs with Intel HD graphics 520, 530 and 620. My old laptop works fine which is using Intel HD Graphic 3000. Other machines with Nvidia cards are working fine too. I believe the problem is on shaders in the sampling loop. My program is using osg 3.2.3. I also tried to upgrade to osg 3.4.1, but the same problem occurred with Intel HD Graphic 520, 530 and 620. Do anyone have similar problem and any solution to fix it? Many thanks.

Regards,
Clement Chu

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Last edited by mp3butcher (Julien Valentin) on Sat Sep 02, 2017 6:20 pm; edited 4 times in total

Recently, I found the problem is related to Intel graphic driver. Specify on latest Intel graphic cards. My work laptop is dell and there is no problem on old Intel graphic card. Since I changed to new dell laptop with latest Intel graphic card, I found the problem is on gl_Vertex which value is not normalised and causes the crash on sampling loop. So far I tested 5 different laptops with different Intel graphic cards. Only Intel graphic card with 3 digit version number will cause the problem (old Intel card is using 4 digit for version).

Hi,
it surely is the duplicate of
http://forum.openscenegraph.org/viewtopic.php?t=14304
I thought this issue was fixed since all this time
The hack i use is there
curious bug indeed, and so curious solution too
@robert
Perhaps it may be merged into master...your call...

cheers

Clement wrote:

Quote:

Hi,

Finally I found where causes the problem. For some reasons, gl_Vertex is not normalized. I looked at osg shader source code (src\osgVolume\Shaders). For example, in file volume_frag.cpp,

vec4 t0 = vertexPos;
vec4 te = cameraPos;

// by default te did to check the range (0 and 1), but t0 did not.
// If I added some codes to check the range, then the problem is completed gone.

I believe the problem is related to GLSL version and latest Intel HD Graphics driver is using higher version of GLSL, but gl_Vertex does not normalize or the value is just over 1 or less then 0 (eg. 1.00001). Then it causes the crash when running the sampling loop. I am not an expert on GLSL, so I would like to confirm the best solution to handle this problem. Thanks.

My program uses RayTracedTechnique for volume rendering, but it hangs with Intel HD graphics 520, 530 and 620. My old laptop works fine which is using Intel HD Graphic 3000. Other machines with Nvidia cards are working fine too. I believe the problem is on shaders in the sampling loop. My program is using osg 3.2.3. I also tried to upgrade to osg 3.4.1, but the same problem occurred with Intel HD Graphic 520, 530 and 620. Do anyone have similar problem and any solution to fix it? Many thanks.

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